Slide-valve fob



UNITED STATES PATENT OFFIOE.

JOHN GLEASON, OF NORTHFIELD, VERMONT.

SLIDE-VALVE FOR STEAM-ENGINES.

Specication of Letters Patent No. 11,607, dated August 29, 1854.

To all whom t may concern Be it known that I, J oI-IN GLEAsoN, ofNorthfield, in the county of Washington and State of Vermont, haveinvented certain new and useful Improvements in Slide-Valves andSteam-Chests of Locomotives and other Steam-Engines; and I do herebydeclare that the following is a full, clear, and exact description ofthe same, reference being had to the accompanying drawings, forming partof this specification, in which- Figures 1 and 2 are both longitudinalsections of a steam chest and slide Valve of a' valve, and the openingof t-he steam ports,-

to the full width, very early in the stroke of the engine.

My invention consists, secondly in the employment in the covering platebefore mentioned of certain safety valves, whereby on the breaking orgiving way of the valve gear all danger of bursting the cylinder by thecompression of the steam in front of the piston is efectually obviatedby allowing the steam to return through the steam` way and valve intothe steam chest.

To enable those skilled in the art to make and use my invention, I willproceed to describe its construction and operation.

The valve seat, A, only diiers from the seat of the common slide valve,in having the steam ports (a, widened to the extent shown in bothfigures of t-he drawing, where the ordinary width, which is the same asthe width of the steam ways, D, D, is indicated by blue lines. Thisenlargement it will be seen is all on the outside, and is gradualcommencing a short distance down the passage, and it makes the width ofthe ports about one-third greater than that of the steam ways.

The construction ofthe valve, B, will be best understood by reference toFig. 1. It is made of uniform thickness, from end to end, and is facedparallel on its upper and Its length is such that when` in the center ofthe valve through which the steamhis exhausted is of such length as tobe capable of extending exactly from the inner edge of one steam port,to the inner edge of the other, and from this cavity (b) there is anopening (7c) through the back` of the valve, which is of the same lengthas, but wider than, the exhaust port (c). Midway between the cavity (b)and the ends of the valve, there are two passages (d, d) of the samelength as the steam port-s, and of the same width as the steam ways, D,D', at the part where there is no enlargement. The parts (f, f) of thefaces of the valve, between the ends of the valve, and the outer sidesof the passages, and the parts (e, e) between the said passages* and theexhaust cavity (b) are all exactly equal in width, to the excess of thewidth of the steam ports above that of their passages, so that wheneither of the said parts of the face cover the ports, the port is stillopen to the full effective width, equal to the width of the steam way.The passages, through the valve do not extend directly upward squarewith the face but are curved toward the center.

The covering plate, C, is intended to be made of cast iron and bolted tothe cover of the steam chest. It is faced on its under side to fitclosely to the back of the valve, and in its face, there are twocavities, (g, g) the outer sides (it, 7L) of which are directly oppositethe outer edges of the steam ports, and the inner edges, (i, i) of whichare at a distance apart equal to the width of the opening (7c) in theback of the valve.

The operation of the slide valve is best illustrated in Fig. 2, where itis supposed to be moving in the direction of the black arrow, and isrepresented in black outlines and tinted, in the position it occupies,while- 1passes over the valve, through the cavity (g) in the coveringplate, and the passage (d) in the direction of the red arrows (2, 3, 4,)and enters the port (a) by that course. The valve reaches the positionshown in red outline when the piston has made about onefifth of itsstroke, and it will be understood, that as the space between the end ofthe valve, and the outer edge of the port, is then equal to half thewidthv of the steam -way, and the space between the top edge of Vthevalve, and the edge of the cavity (g) is of the same width, that thefull width of 'opening is obtained-The partsk (f) and (e) of the face ofthe valve being of no greater width, than the excess of width of theport, always give the full amount of opening at the port, provided thereAis opening enough at the top andv bottom edges of the end of the valve.The full width of opening continues during the retreat-ing motion of thevalve until the piston has arrived very near where the steam is shutoff. The exhaust.

steam escapes from the steam way,'D, directly into the cavity in thedirection of the arrow (5), and also through the passage (cl) the cavity(g) and theopening (la) in the direction of the arrows 6 `8f 7 The gainin time byk this invention in opening the steam and exhaust ports, willbe exactly onehalf, and `in addition to this,` the admission of steam tothe back of they valve to balance it, is 'accomplished without otherprovision being made for that purpose.

The safety valves, E, E, for preventing the bursting of the cylinder,are placed inr the cavities (g, g) of the covering plate, C, and steamspace is left in the steam chest above the said plate. The valves may beof any kno-wn form capable of being lifted by the ressure of steam belowthem. The

cavities (g, g,) are always in communication through the passages (d,0V) with their respective steam ways, D, D', and during the induction ofthe steam through the ports, are balanced by the steam above and below,but if the valve gear should give out, and the valve suddenly becomestationary, leaving no opening for the escape of the steam whichmust'have been left at the time of its stoppage, in one end of thecylinder and' one steam way, Vthe compression of this steam by thecontinued motion of the piston, will cause'the safety valve, E, in thecavity y(g) which is in communication with that steam way, tc be lifted,andk the steam will have free escape into the steam chest.`

This invention can be `applied to any steam engine, previously rusingthe common slide valve, all that is necessary being to enlarge the steamports (ci, d) to the extentrepresented, and construct a new valve,

rB, and apply. a covering plate, C, as de` scribed. If there should notbe sufficient height in the old steam chest, to receive the valve andcovering'plate, a new one may b e `made at little expense compared withthe advantages to be derived. The same eccentric, valve gear &c are allapplicable to the new valve.

What I claim as my invention and desire to secure by Letters Patent` is,

1. The valve B, constructed as described .in combination with thecavities (g, g) in

